1. Field of the Invention
The present invention relates to methods for selectively detaching, patterning, and harvesting cells using near-infrared capable of being used in cell culture and detaching cells without trypsin.
2. Discussion of Related Art
Stem cells are cells having capabilities of self-replication and differentiation into at least two cells, and may be classified into totipotent stem cells, pluripotent stem cells, and multipotent stem cells.
Recently, therapeutic methods using such stem cells capable of being continuously self-replicated and differentiated into various tissues in the body are widely used, boosted by development of biotechnology. Particularly, such methods start to be used to treat incurable diseases such as Parkinson's disease, cancer, diabetes, etc. as well as human organ regeneration (Miyahara Y. et al., Nature Medicine, 12(4), 459-465, 2006; Kang, K. S. et al., Stem Cells, 24(6), 1620-1626, 2006; Silva, G. V. et al., Circulation, 18, 111, 2005). While various therapeutic methods using stem cells have been developed so far, there is still less research on the characteristics of stem cells, and there is a limit to treatment using stem cells due to limits to proliferation and differentiation of stem cells.
Generally, it is known that a fate of differentiated stem cells is often influenced by a cell to cell, and a cell to extracellular matrix (ECM) including growth factors, and also by an instructive environment (Nakayama et al, Neurosci Res, 46, 241-249, 2003). Recently, as research on interaction between an environment of stem cells and the stem cells, a bioengineering field is emerging. It is not a method of controlling a hormone, growth factor, or serum included in a cell culture, which is conventionally used in research or induction of the function of a cell, but a method of controlling attachment, proliferation, differentiation, and secretion to an extracellular matrix, which are characteristics of a cell, through interaction between a support to which the cell is attached and grown and the cell (Bauer S. et al., Acta Biomaterialia, 4, 1576-1582, 2008; Guo L. et al., Biomaterials, 29, 23-32, 2008). To this end, chemical surface modification which is used to develop a material having biocompatibility and change a surface characteristic is a critical factor.
The pluripotent stem cells can be differentiated into various cells and tissues derived from an ectoderm, a mesoderm, and an endoderm. These cells are derived from an inner cell mass located in a blastocyst generated after 4 to 5 days of fertilization, and called embryo stem cells. They are differentiated into various different tissues, but do not create a new organism.
The multipotent stem cells can be only differentiated into cells specific to tissues and organs in which these cells are included. They are involved in growth and development of tissues and organs in an embryonic period, a neonatal period, and an adult period, and functions of maintaining homeostasis of adult tissues and inducing regeneration of damaged tissues, and tissue-specific multipotent stem cells are generally called adult stem cells.
The adult stem cells are found in a stage in which individual organs of embryos are formed after development or at an adult stage, and differentiated only into cells generally constituting a specific tissue. Such adult stem cells serve to replenish the loss of cells normally or pathologically occurring in most of organs in an adult. Exemplary adult stem cells include hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs). It is known that the HSCs are usually differentiated into blood cells in blood such as erythrocytes, leukocytes, and thrombocytes, and the MSCs are differentiated into cells of mesodermal tissues such as osteoblasts, chondroblasts, adipocytes, and myoblasts.
Stems cells can be differentiated into various cells according to how to differentiate or treat the stem cells. To control the differentiation capability of the stem cells, it is important to research and control the interaction between cell-to-cell and cell-to-extracellular matrix (ECM) including growth factors.
Generally, as a conventional technique to detach cells, an enzyme called trypsin is widely used. The trypsin chemically damages a bond in a cell attached to a cell culture container, resulting in damage to a cell wall or a protein present in the cell wall of a stem cell. Accordingly, when the trypsin is used, stem cells may be damaged, and thus degradation in proliferation capacity and differentiation potency may occur. In addition, since the trypsin is treated entirely to a culture container, it may be difficult to partially obtain a desired cell.
For this reason, there is a demand for developing a new technique to easily detach cells from a culture container, and to detach cells only from a desired part without damage to the cells.